A cluster tool type is well-known as a type of a vacuum processing apparatus having a vacuum transfer chamber. In the cluster tool type apparatus, a plurality of process chambers, where predetermined processes are performed at a depressurized state, are disposed around a vacuum platform so as to promote consistency, connectivity, or compositeness of processes. The cluster tool type is also referred to as a multi-chamber type, and is typically employed by a semiconductor manufacturing apparatus (for example, refer to Patent Document 1).
Generally, in a cluster tool, one target object is sequentially transferred to the plurality of process chambers so that the same type or different types of vacuum process is continuously performed on the target object. In the semiconductor device manufacture, a CVD (chemical vapor deposition), sputtering, dry etching, dry cleaning, etc. are the representative vacuum processes performed in the cluster tool.
Since the transferring of the target object throughout the plurality of process chambers is performed through the platform, the interior of the platform always maintains a depressurized state. In order to transfer an unprocessed target object from an atmosphere space to the platform, and to transfer the target object, on which a series of vacuum processes have been finished, out from the platform to the atmosphere space, a load lock chamber of an atmosphere/vacuum interface is also connected to the platform through a gate valve. A vacuum transfer apparatus for receiving/delivering a substrate between each process chamber or the load lock chamber, and the vacuum transfer apparatus at a depressurized state is formed inside the platform. Such a type of vacuum transfer apparatus includes a stretchable transfer arm so as to transfer the target object from and to each process chamber or the load lock chamber, and may rotate the transfer arm according to an access point.
However, in the vacuum processing apparatus of the cluster tool type, a layout, wherein the width size of the entire apparatus, when viewed from a load port side through which a target object cassette is inserted or ejected, is reduced or maintained while the platform is extended long in an inner depth direction thereby installing additional process chambers along the long side of the platform to increase the number of installed chambers in the entire apparatus, has become a trend as a method to advantageously deal with increasing size of a semiconductor wafer (for example, refer to Patent Document 2).
As such, when the number of installed process chambers increases, the burden of the vacuum transfer apparatus increases, and thus a transfer capability of a vacuum transfer apparatus side failing to follow an entire process capability of a processing apparatus side has become a problem.
In this regard, a conventional cluster tool forming one vacuum transfer robot inside a platform uses a method of setting a module cycle time to have substantially the same length, wherein the module cycle time is obtained by adding a stay time of one target object staying in each chamber, to accompanying busy times when a function of a module is stopped due to the target object before and after the stay of the target object with respect to a plurality of process modules connected to the platform, of the vacuum transfer robot, which has two transfer arms, circling the plurality of process modules in the same order as each target object makes a round, and of transferring out (pick) a target object that has been processed through access into each process module by using one of the two transfer arms and alternately transferring in (place) another target object instead of the target object that has been processed by using the other transfer arm (for example, refer to Patent Document 3).
Although, such a circulating pick and place method effectively functions when a process time of each process module is sufficiently long compared to a transfer time, since a transfer operation of the transfer robot has a time to spare, when the process time is short, it becomes difficult for the transfer robot to respond, and thus transfer efficiency or throughput decreases. Meanwhile, if a post-process (for example, purging, cleaning, or the like), which is performed in the process module immediately after the target object that has been processed is transferred out (picked), takes a long time, the transfer robot has to wait in front of the process module until the post-process is completed so as to perform a place operation with respect to the possessed unprocessed target object, and thus throughput of the overall system remarkably deteriorates due to this long standby time.
Also, due to the trend of the increasing number of installed process modules (process chambers) as described above, performing all substrate transfer operations in the platform by using one vacuum transfer robot has reached the limit.
In Patent Document 4, in order to remove the limit to the transfer capability of the platform using one vacuum transfer robot in the cluster tool, the present inventor suggests a vacuum processing apparatus, wherein two movable stages or two arm mechanisms in a common narrow transfer space are moved in an up and down direction and a horizontal direction by two movable stage driving mechanisms in the platform so that the two movable stages or two arm mechanisms switch the locations with each other in the up and down direction in a horizontal state without interfering with each other.    (Patent Document 1) Japanese Laid-Open Patent Publication No. hei 8-46013    (Patent Document 2) Japanese Laid-Open Patent Publication No. 2007-12720    (Patent Document 3) Japanese Laid-Open Patent Publication No. 2006-190894    (Patent Document 4) Japanese Laid-Open Patent Publication No. 2004-265947